Zhuo Chunliu, Wang Xin, Docampo-Palacios Maite, Sanders Brian C, Engle Nancy L, Tschaplinski Timothy J, Hendry John I, Maranas Costas D, Chen Fang, Dixon Richard A
BioDiscovery Institute and Department of Biological Sciences, University of North Texas, 1155 Union Circle #311428, Denton, TX 76203, USA.
Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Sci Adv. 2022 Mar 11;8(10):eabm8145. doi: 10.1126/sciadv.abm8145. Epub 2022 Mar 9.
The factors controlling lignin composition remain unclear. Catechyl (C)-lignin is a homopolymer of caffeyl alcohol with unique properties as a biomaterial and precursor of industrial chemicals. The lignin synthesized in the seed coat of switches from guaiacyl (G)- to C-lignin at around 12 to 14 days after pollination (DAP), associated with a rerouting of the monolignol pathway. Lack of synthesis of caffeyl alcohol limits C-lignin formation before around 12 DAP, but coniferyl alcohol is still synthesized and highly accumulated after 14 DAP. We propose a model in which, during C-lignin biosynthesis, caffeyl alcohol noncompetitively inhibits oxidation of coniferyl alcohol by cell wall laccases, a process that might limit movement of coniferyl alcohol to the apoplast. Developmental changes in both substrate availability and laccase specificity together account for the metabolic fates of G- and C-monolignols in the seed coat.
控制木质素组成的因素仍不清楚。儿茶酚型（C）-木质素是咖啡醇的同聚物，作为一种生物材料和工业化学品的前体具有独特的性质。授粉后约12至14天，种皮中合成的木质素从愈创木酚型（G）-木质素转变为C-木质素，这与单木质醇途径的重新定向有关。咖啡醇合成的缺乏限制了授粉后约12天前C-木质素的形成，但在14天后松柏醇仍在合成并高度积累。我们提出了一个模型，即在C-木质素生物合成过程中，咖啡醇非竞争性抑制细胞壁漆酶对松柏醇的氧化，这一过程可能会限制松柏醇向质外体的移动。底物可用性和漆酶特异性的发育变化共同决定了种皮中G-和C-单木质醇的代谢命运。
